I’m nearing the end of building my SA drift car, and am at the point to where it’s time to order my carb. For context this will be a drift car mainly that’s sometimes driven on the street. The motor setup is a tall port 12a half bridge with lightened/balanced/clearances rotors, rx8 stat gears, and a RB header with a dual exhaust that collects at the axle. I’m wanting to stay Weber since it’s what i somewhat know and have a friends who knows them well. I’m leaning towards the 51 IDA but i’ve heard mixed things wether to go 48 or 51 or bridges. I know that the 36 DCD would be the best option for my port use, but since this car will be driven hard I want serviceability to be a big priority and from what a friend has told me finding parts for the DCD are a PITA. I’m open to suggestions as well but any information would be helpful.

 

An IDA would be my choice. As far as 48mm vs 51mm....there really isn't much of a difference because they both use the same chokes. Typically a 51mm IDA is just a bored out 48mm IDA with 3mm bigger throttle butterflies fitted. Of note, this does make the area around the idle screws more fragile so care has to be taken when making idle adjustments. Either would be fine.

I bought an EMPI - EPC51 back in 2012 or so. I selected it because it was cheap, came with a larger fuel bowl and most importantly has an additional idle port/slot that did not come on Weber IDAs. The purpose of the additional idle slot was to aid with off idle performance. Look for this update when searching for a carb. My racer friends used to pay big bucks to have this kind of change made to their Italian IDAs.

I would recommend the EMPI if you can find one for sale. They use Weber parts and are just an IDA knock off. They aren't cheap anymore but then nothing is. Search places like Pierce Manifold and on air cooled VW specialty sites for carbs and parts.

 

Wow that sounds really nice. Basically just a better 48 IDA it seems. Is there anything specific you have to do with these differently setup wise with having the two changes or is it basically the same as the 48?

 

In my experience, all Weber IDAs and knock off IDAs (like my EMPI) are the same in terms of the flange bolt pattern and the tune up parts they use. So if an item fits an IDA it will fit any IDA....so jets, emulsion tubes, chokes, throttle cable adapters, etc.

Looks like Mazdatrix has a good inventory of carbs and parts. https://mazdatrix.com/product-catego...lds-and-parts/

The only variable is the intake manifold. Some intakes mount an IDA with the fuel inlet pointed towards the left side of the car (driver's side) and others put the fuel inlet pointed to the right side of the car. This determines the type of shaft lever that needs to be used with the carb. Mazdatrix sells both styles. It also affects how fuel lines are routed. My intake points the fuel inlet to the left.

 

Would be it be more advantageous to have it running on way over the other? I’m doing AN fuel lines so it won’t be terrible for routing

 

Other than one of the Cable Adapters that Mazdatirx sells is more expensive than the other there is no advantage one way or the other. I inherited the intake manifold I am using from another racer so I just went from there.

 

Just to add my two cents , I currently and in the past , use(d) both 48/51IDA's and the Rotary Engineering Dual 36DCD set up. Of course the engine build and application will dictate which one to use , but with a half bridge , a progressive secondary system would be preferred ( 36DCD's or Holley) . When I have dynoed two different engines ( a 12A and 13B) with both carb types , it showed more top end power and a flatter power band with the dual DCD's. For drifting ( and in my case Auto-X) , a sharp throttle response is desired and the IDA is better suited. Your power band may be narrower
but can be tailored to gearing , track etc accordingly.
Both types of carbs are easy to service re-jet , get parts for etc. The DCD series is akin to all Weber 2bbl downdraft like the DGV , and 32/36' s found everywhere.